Path Planning And Simulation Analysis Of Automatic Parking System For Passenger Car

With the further increase of car ownership,the scarce parking space become more nervousv and parking become more difficult in big cities.Traffic accidents caused by the parking error has become a common type of traffic accident.In view of the existing parking path planning study which neglected the actual vehicle steering constraints and initial position conditions,the planned path curvature is discontinuous and inconsistent with the initial position of the vehicle and it affects the actual vehicle tracking effect.In order to solve this problem,the parking path planning method is studied based on the actual parking conditions,vehicle movement constraint and environment constraint.At first,the motion process of vehicle is studied and the vehicle kinematics model is set up,at the same time,the geometry relationship betweem the car body and body reference point is derived to figure out the movement of the body reference point and the overall profile with the input of speed and steering wheel.Secondly,based on the traditional path,the minimum parking size,the allowable deflection angle range and the feasible starting area of the single-step parallel parking condition is studied.The conditions of environmental constraints and vehicle kinematics constraints of single step parallel parking are analyzed.Based on the b-spline theory,a nonlinear constraint single step parallel parking path optimization function is established.On this basis,according to the actual condition of parking,the MATLAB path planning simulation is conducted for the initial position of conventional parking and the initial position of the tilted parking,in order to verify the rationality of the path planning method.Then,based on non-time reference path tracking control and terminal sliding mode control method,a non-time reference terminal sliding mode tracking control method based on approach law is proposed.The non-time reference method is applied to avoid the influence of vehicle speed control and reduce the speed control requirement.Combining with the terminal sliding mode control method based on the reaching law,the controller controls the vehicle tracking to the reference path,reduces the tracking error,improves the approach quality and reduces the buffing phenomenon.The effect of the design controller is verified by tracking the sinusoidal reference path on Simulink.Based on the Simulink and Carsim software,the path planning and tracking simulation of the normal initial position and the tilt initial position were conducted respectively.Finally,the rationality of the planning path and the control effect of the path tracking controller are verified through the actual parking experiment.